Sealed rolling bearing

Abstract

When a sealed rolling bearing is subjected to temperature increase caused by the friction heat of the seal and external heat and is subsequently cooled down, negative pressure is created in an internal space of the bearing and causes a seal lip of the bearing to stick to a seal groove, resulting in abrasion of the seal lip. The present invention solves the problem while maintaining sealing performance of the seal lip. In a sealed rolling bearing in which a sealing member has a seal lip on its edge and the seal lip abuts against a raceway-side groove wall of a seal groove adjacent to an inner raceway, the seal lip has a contact tip shaped into an arc whose radius of curvature R ranges from 0.1 mm to less than 0.2 mm.

1 . A sealed rolling bearing comprising:
 an inner ring including an inner raceway on its outer peripheral surface;   an outer ring including an outer raceway on its inner peripheral surface;   a plurality of rolling elements rotatably disposed between the inner raceway and the outer raceway; and   a sealing member sealing an internal space between the inner raceway and the outer raceway, wherein   the outer ring has a groove at a side of the outer raceway on the inner peripheral surface, the groove engaged with an outer rim of the sealing member,   the inner ring has a seal groove at a side of the inner raceway on the outer peripheral surface and a shoulder portion between the seal groove and an edge of the inner ring, the sealing member being in contact with the seal groove,   the sealing member is made of an elastic member and a metal core reinforcing the elastic member, is shaped into an annulus as a whole and includes an engaging portion fitted entirely into the groove formed on the inner peripheral surface of the outer ring and a seal lip formed at an edge of the elastic member,   the seal lip abuts against the raceway-side groove wall of the seal groove adjacent to the inner raceway,   the seal lip has an arc-shaped contact tip, and   the contact tip has a radius of curvature R ranging from 0.1 mm to less than 0.2 mm.   
   
   
       2 . The sealed rolling bearing according to  claim 1 , wherein
 a tangent line at the extremity of the arc-shaped contact tip is parallel with the raceway-side groove wall of the seal groove adjacent to the inner raceway.   
   
   
       3 . The sealed rolling bearing according to  claim 1 , wherein
 the sealing member includes a labyrinth lip integrally formed with the seal lip, the seal lip is in contact with the raceway-side groove wall of the seal groove, and the labyrinth lip projects above the shoulder portion.   
   
   
       4 . The sealed rolling bearing according to  claim 1 , wherein
 a shoulder portion-side corner is formed on the boundary between the shoulder portion-side groove wall of the seal groove and the shoulder portion,   the bottom surface of the seal lip is continuously connected with the bottom surface of the labyrinth lip through a step portion located above the shoulder portion-side groove wall of the seal groove, the diameter of the bottom surface of the labyrinth lip being larger than that of the seal lip,   the shoulder portion, and the shoulder portion-side groove wall, and the shoulder portion-side corner form a bent wall on the inner ring, while the step portion and the bottom surfaces form a bent wall on the sealing member, the bent walls face each other, and a clearance created between the bent walls defines a labyrinth seal.   
   
   
       5 . The sealed rolling bearing according to  claim 4 , wherein
 the shoulder portion is smaller in diameter than a raceway-side flat surface adjacent to the inner raceway by size S.   
   
   
       6 . The sealed rolling bearing according to  claim 5 , wherein
 the bottom surface of the labyrinth lip is inclined at a constant angle θ with respect to the shoulder portion.   
   
   
       7 . The sealed rolling bearing according to  claim 1 , wherein
 the elastic member of the sealing member is made of any one of nitrile rubber, acrylic rubber and fluorine-contained rubber.   
   
   
       8 . The sealed rolling bearing according to  claim 1  is applicable to any one of pulleys, alternators and electromagnetic clutches.